The invention relates in particular to an apparatus for effecting automatic bobbin-changing on winding-up machines or bobbin-winders possessing at least one horizontal yarn support on which the yarn, delivered continuously, is wound up at high speed. By "high speed", there are to be understood speeds which can be much as 6,000 to 7,000 meters/minute and more.
Automatic bobbin-winders provided with individual bobbin-changing means are known. French application No. 2,168,645 relates to a bobbin-winder provided with a longitudinally slit tube for effecting pneumatic conveying, which makes it possible for the yarn to be conveyed towards a waste receptacle when the support is being changed. Moreover, means for removing the full bobbin and placing the empty bobbin in position are integrated into the actual structure of the bobbin-winder. This system leads to a particular design of the bobbin-winder, which has three spindles for mounting bobbins, each of them being used in turn to form a single bobbin at a time.
The investment in equipment is high and this equipment is unused for a considerable proportion of the time. Moreover, the failure of any one of the bobbin-changing components makes it necessary to stop the bobbin-winder which cannot operate under manual control.
A bobbin-winder equipped with bobbin-changing means is also known from U.S. Pat. No. 3,761,029 in which two yarn supports are alternately in contact with a winding cylinder and which possesses an associated transfer device equipped with pneumatic means for temporarily removing the yarn to a waste receptacle and for passing it from the full bobbin to the empty bobbin while forming an attachment tail. The bobbin-changing operation involves a manual sequence for removing the full bobbin and placing the empty bobbin in position.
French Pat. No. 2,105,351 relates to a device for effecting the entirely automatic changing of yarn packages on a texturizing loom. It consists of a movable assembly which travels along the loom like a carriage and serves all the winding-up positions of the loom. The device includes means for removing the full bobbin, means for placing an empty bobbin in position and means which continuously remove the yarn to a waste receptacle when the bobbin is being changed, in order to prevent the yarn from remaining in the ovens for a long time, as this could damage the yarn. The removal means consist of a nozzle which is mounted so that it can move and which can suck up a yarn, remove it temporarily to a wate receptacle and then anchor it on the empty bobbin. This device avoids the disadvantages of prior art devices, because a single device serves a large number of winding-up positions. However, the yarn comes under the control of the removal nozzle after contact between the package and the drive or winding cylinder has ceased and after the yarn has been removed from the reciprocating guide. The nozzle thus acts on a yarn which is no longer pulled. This device, which was investigated on a texturizing loom where the maximum winding-up speed (not indicated in the patent) is approximately 400 to 500 meters/minute.
French Pat. No. 2,027,080 describes an automatic bobbin-changing apparatus which can serve several rows of bobbin-winders. The apparatus has means which make it possible automatically to remove the full bobbin and place an empty bobbin in position, means for gripping the yarn and removing it to the waste receptacle when the bobbin is being changed, and means for transferring the yarn onto the empty bobbin. The means for gripping and removing the yarn comprise a capture head provided with a cutting device and means for sucking up the yarn, acting at the level where the yarn sweeps a triangular area, that is to say between the last fixed guide and the reciprocating guide for effecting distribution of the yarn on the bobbin. The head travels in a direction which is substantially perpendicular to the plane of movement of the yarn, and the yarn enters a cavity provided in the head and is then cut and thereafter sucked towards the waste receptacle. It is found that the yarn is gripped, after the cutting operation, on an end which is no longer pulled, and this is incompatible with high speeds of delivery of the yarn. Furthermore, what is involved is a device for effecting bobbin-changing on a bobbin-winder where the yarn is wound up at a speed of 150 meters/minute, under a tension, of 1 gram. Moreover, the bobbin-winder has a special structure according to which the receiving bobbin is rotated via its ends by means of rollers.
French Pat. No. 2,098,134 relates to a method and apparatus for effecting bobbin-changing on a bobbin-winder. Bobbin-changing means are mounted in a stationary manner at each winding-up position. The apparatus has a fixed nozzle for gripping the yarn, the nozzle being provided with a capture slit and acting at the level where the yarn sweeps a triangular area as above. In operation, contact between the coil and the winding cylinder is first stopped and the nozzle then comes into action again. The nozzle thus acts on a loose yarn which is no longer pulled. This principle can be applied only at low winding-up speeds. Moreover, since the yarn is loose, its path becomes inexact and capture by the nozzle becomes uncertain. The reliability of the device is thus questionable.
Thus, at the present time, no device exists which can effect automatic bobbin-changing on a bobbin-winder which operates at high speed.